The present invention relates to a system and apparatus for testing of lasers, lasers accessories and electro-optical devices such as cameras, thermal imagers, and other vision devices. One of issue associated with testing these devices is how well the devices work in the rain or fog. One valuable aspect of testing these devices is determining consistently how far the devices may penetrate through various external conditions. For instance, how well an image can be seen through rain or fog and how much information a laser can transmit through the rain or fog. Another important aspect for testing these devices is ensuring an accurate correlation between an actual and simulated type of rain or fog that electro-optical devices are being tested in. For example, was it a light drizzle, a torrential downpour, or a condition in the middle?